How to change the background of the page when it loads without having to click the button?
import img1 from '../images/img1.jpg';
import img2 from '../images/img2.jpg';
import img3 from '../images/img3.jpg';
const [background, setBackground] = useState(img1);
const list = [img1, img2, img3];
const css = {
backgroundImage: `url(${background})`,
};
return (
<div style={css}>
<button onLoad={() => setBackground(list)}>Change background</button>
</div>
);
but setBackground(list)} does not read the array and the onLoad event does not work when the page is reloaded.
thanks for any help!
As mentioned above the solution requires localStorage, useEffect, useRef. All logic is inside useEffect, because when the component is mounting all the magic happens here. working example
App.js
import { useState, useEffect, useRef } from "react";
export default function App() {
const img1 = "https://dummyimage.com/400x200/a648a6/e3e4e8.png";
const img2 = "https://dummyimage.com/400x200/4e49a6/e3e4e8.png";
const img3 = "https://dummyimage.com/400x200/077d32/e3e4e8.png";
let [lsNum, setLsNum] = useState(0);
// Absolute number '1'
let count = useRef(1);
const list = [img1, img2, img3];
useEffect(() => {
// Get value from localStorage, transform to number
const lS = Number(localStorage.getItem("image"));
// Check! If localStorage have number 2 / more
// Set number 0
if (lS >= 2) {
localStorage.setItem("image", 0);
return;
}
// Get absolute number and increase with number from localStorage
count.current = count.current + lS;
// Set result to state
setLsNum(count.current);
// Set the resulting number to localStorage
localStorage.setItem("image", count.current);
}, []);
const css = {
height: "200px",
width: "400px",
display: "block",
backgroundImage: `url(${list[lsNum]})`, // index change
backgroundPosition: "center",
backgroundSize: "cover",
border: "1px solid red"
};
return (
<div className="App">
<div style={css}></div>
</div>
);
}